The present invention relates to a display apparatus suitable for operating a computer or various electronic appliances such that an operator can operate the computer or the electronic appliances while viewing display of the display apparatus.
FIG. 1 shows one example of a display unit 60 of a known display apparatus disclosed in Japanese Application No. 63-93845 filed Apr. 15, 1988. As taught in that application, and as further taught in Japanese Patent Application No. 63-108778, filed Apr. 30, 1988, an operator puts on the known display apparatus as shown in FIG. 2. In FIG. 1, an LED array 61 acting as a light source is provided at a lower portion of a casing 62. The LED array 61 is formed by a one-dimensional high-density monolithic array of, for example, 32 dots/mm or so. In FIG. 1, only one element of the LED array 61 is shown but actually, a plurality of the elements are arranged in series in the direction perpendicular to the sheet of FIG. 1. Supposing that the LED array 61 has a length of, for example, about 8.4 mm, a total of the elements are constituted by 280 dots. In order to obtain a two-dimensional image of the light source, a vibrating mirror 63 is provided so as to confront the light source. A resonance type scanner 64 is provided for vibrating the vibrating mirror 63 at high speed. When the LED array 61 is flickered in response to a data signal synchronously with vibrations of the vibrating mirror 63, a planar image is reflected in the vibrating mirror 63 as a virtual image. Thus, signals for one picture are transmitted during one period of vibrations of the vibrating mirror 63. The LED array 61 is provided at a focal point of a lens 65. Light from the LED array 61 is reflected by the vibrating mirror 63 and is changed into parallel light by the lens 65 such that the parallel light reaches an eye 66 of the operator. In this case, the lens 65 may also be provided between the LED array 61 and the vibrating mirror 63.
As shown in FIG. 2, the display unit 60 is attached to one end of a frame 70 and the other end of the frame 70 is mounted on a head set 72 through a rotary support member 71. The display unit 60 is rotated about the rotary support member 71 in a lateral direction so as to be changed over to an observational position and a nonobservational position. Meanwhile, a lead wire 73 is attached to a garment of the operator by a clip 74 so as not to disturb operation of the computer or the electronic appliances and is connected to a host portion (not shown) placed at another location. The operator puts the head set 72 on his head and positions the display unit 60 in front of an eye of the operator so as to view an image displayed by the display unit 60.
Meanwhile, in the known display apparatus referred to above, such a problem arises that since the display unit 60 obstructs the operator from viewing a subject or a scene in front of the display unit 60, it is difficult for the operator to manipulate switches, etc. in front of the display unit 60 while viewing an image displayed by the display unit 60. Furthermore, the display known apparatus has such a drawback that since an image, for example, a red image is displayed in the black background in the display unit 60, the eye of the operator is readily fatigued.
As shown in FIG. 3, a display window 68 is provided at either one of right and left sides of the display unit 60 such that the operator can view the background, e.g. a keyboard of the computer with one of his eyes while viewing a screen of the display unit 60 with the other one of his eyes. FIG. 3 shows a case in which the operator views the background with his right eye while viewing the screen of the display unit 60 with his left eye. In the case where the operator views the background with his left eye while viewing the screen of the display unit 60 with his right eye by using the display unit 60, the display unit 60 may be turned upside down as shown in FIG. 4. However, when the display unit 60 has been turned upside down, a picture on the screen of the display unit 60 is also seen upside down if no measures are not taken. Thus, a changeover switch 69 for changing over vertical orientation of the picture is provided. If the displayed picture is seen upside down, vertical orientation of the picture is changed over by operating the changeover switch 69.
Meanwhile, image signals corresponding to one page of the screen of the display unit 60 are stored in a data storage formed by, for example, a DRAM (dynamic random access memory) provided at the host portion so as to be transferred to the LED array 61 through the lead wire 73. However, in the case where vertical orientation of the picture of the display unit 60 has been changed over by operating the changeover switch 69, picture elements to be transferred are transmitted by converting sequence of transfer of the picture elements.
However, the methods disclosed in Japanese Patent Applications 63-93845 and 63-108778 have an inconvenience in that the circuit configuration used becomes complicated for the following reason. The LED array 61 is usually provided in a zigzag shape so as to increase density of the picture elements such that one column of the LED array 61 are turned on several rows later than the other column of the LED array 61. FIG. 5 shows prior art LED drivers 81 and 82 for driving the LED array 61. In the LED array 61, one column of 100 LEDs 1D to 100D of 100 dots and the other column of 100 LEDs 1E to 100E of 100 dots are staggered so as to have 200 dots. The two columns are spaced a distance corresponding to three rows from each other. By wire bonding, the LED array 61 is connected to the LED drivers 81 and 82 including a shift register and a latch. Characters Dd and De denote image signals and the arrow X represents a scanning direction based on vibrations of the mirror.
If an image of one column formed by the image signals Dd and De is displayed on a straight line by an array of 200 dots, namely, 1D, 1E, 2D, 2E,--99D, 99E, 100D and 100E, the LEDs 1D to 100D are required to be turned on later than the LEDs 1E to 100E by a duration corresponding to three rows. Thus, although there is time difference between turning on of the two columns of the LEDs, the turned on images are seen as being arranged in a column of the LEDs 1D, 1E, 2D, 2E,--99D, 99E, 100D and 100E by effect of afterimage. Characters SR1, SR2, SR3 and SR4 denote 100-bit shift registers for making the above mentioned time difference of three rows. The shift registers SR2 and SR3 are not used for making the time difference but are used for changing sequence of array so as to prevent formation of reverse array caused by the fact that the LED drivers 81 and 82 are constituted by an identical element. If a bidirectional shift register having up/down function is employed as a shift register SR0 of the LED drivers 81 and 82, the shift registers SR2 and SR3 can be deleted.
In the above described circuit configuration, it will be readily seen that if correspondence between a bit map of display and a bit map of memory is obtained, it is difficult that changeover of vertical orientation of the displayed image through change of sequence of the image signals Dd and De is performed by merely converting sequence of transfer of the picture elements from the data storage.
Therefore, the known display apparatus described in the two applications above has been disadvantageous in that the circuit configuration becomes complicated in order to change over vertical orientation of the picture in response to changeover of vertical orientation of the display apparatus.